Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current assets
Cash and cash equivalents	$ 4,178	$ 10,284
Certificates of deposit	266	1,335
Accounts receivable
Oil and natural gas revenues	17,046	9,237
Joint interest billings	4,252	2,488
Other	591	1,447
Derivative instruments	6,395	8,989
Lease and well equipment inventory	1,478	1,343
Prepaid expenses	974	1,153
Total current assets	35,180	36,276
Oil and natural gas properties, full-cost method
Evaluated	654,292	423,945
Unproved and unevaluated	164,514	162,598
Other property and equipment	24,597	18,764
Less accumulated depletion, depreciation and amortization	(295,042)	(205,442)
Net property and equipment	548,361	399,865
Other assets
Derivative instruments	1,880	847
Deferred income taxes	1,878	1,594
Other assets	1,537	887
Total other assets	5,295	3,328
Total assets	588,836	439,469
Current liabilities
Accounts payable	17,364	18,841
Accrued liabilities	50,262	25,439
Royalties payable	5,920	1,855
Borrowings under Credit Agreement		25,000
Derivative instruments		171
Advances from joint interest owners	1,782
Income taxes payable	188
Deferred income taxes	1,878	3,024
Dividends payable - Class B		69
Other current liabilities	56	177
Total current liabilities	77,450	74,576
Long-term liabilities
Borrowings under Credit Agreement	106,000	88,000
Asset retirement obligations	4,551	3,935
Derivative instruments	142	383
Other long-term liabilities	1,465	1,060
Total long-term liabilities	112,158	93,378
Commitments and contingencies (Note 10)
Shareholders' equity
Additional paid-in capital	403,248	263,562
Retained earnings	6,178	18,279
Treasury stock, at cost, 1,192,509 and 1,179,175 shares, respectively	(10,765)	(10,765)
Total shareholders' equity	399,228	271,515
Total liabilities and shareholders' equity	588,836	439,469
Class A
Shareholders' equity
Common stock	567	429
Class B
Shareholders' equity
Common stock		$ 10